Questions about psychology. Answers that work.

How Reliable is Eyewitness Testimony?

In 1984, Maryland USA, Kirk Bloodsworth was given the death penalty. His conviction was based solely on 5 eye-witnesses who all claimed to have seen him commit a horrific crime. After 9 years on death row, he was exonerated by DNA evidence. He was innocent.

There are hundreds of cases of innocent people who, like Kirk Bloodsworth, have been wrongly convicted for a crime. Many of them were sentenced primarily because of eyewitness testimony, and their innocence has come to light since the DNA revolution at the end of the 1980s.

Eyewitnesses are one of the most vital sources of information in any police investigation. They provide significant details that help to narrow the search, uncover more information or even identify the criminal.

However…with so many false convictions, how reliable is it?

How Memory Works

A recent survey found that 63% of US adults think that memory is ‘passive’, like a video camera.

Most persons believe that memory records events exactly as they occur, and can be replayed at any time. They are therefore confident that eyewitness testimony is an accurate source of evidence.

This is quite a staggering stat as these are the same people who make up juries and help to dispense justice. Influenced by a popular misconception, these persons could find someone guilty of a crime based upon nothing more than a single witness’ memory.

As you might have surmised, memory does not work like a video camera.

Memory was first reported as ‘active’ in 1932 by Frederick Bartlett. Since then, psychologists have been diligently trying to uncover the way that memory works. What we do know for certain is that we don’t see something and store it perfectly in our brains until we want to recall it. Our memories are reconstructed and are “more akin to putting puzzle pieces together”, says E. Lotus of the Psychology Department, University of California.

Our memories are vulnerable to error. We can miss details in a scene, and we can be led by suggestion to ‘recall’ things that never happened.

Ways Our Memory Can Be Influenced

In real-life eye-witness testimony, psychologists claim that errors can be made due a wide variety of factors.

This includes the stress experienced at the time the memory was created; higher heart rate, faster breathing, panic. Stress is an even greater distraction if the perpetrator has a weapon. This is called ‘weapon focus’.

There are many who argue that an eyewitness’ memory can be influenced by factors such as the investigating police officers, other witnesses and any media surrounding the case. And there have been endless amounts of studies to support these theories.

Positive Feedback

An interesting study by Well and Bradford in 1999, saw a group of participants watch a ‘blurred’ videotape of a shop robbery. Afterwards they were given 5 photographs, and asked if they could identify the robber in any of them. What they didn’t know, was that the real robber’s photo was excluded.

All participants incorrectly identified the criminal from the photos. After some positive feedback (reassuring words etc.) participants became more confident, and were now ‘certain’ they had identified the criminal.

This shows that the level of certainty a witness has over their memory recall can be affected by those around them. This study in particular, shows how an individual’s memory can be exploited through the use of encouraging words. A witness overstating his or her ability to “single out the criminal” can be very convincing to the jury, and if incorrect, it can be extremely damaging to the final decision.

Other Witnesses and Media

‘Rolling news societies’ such as the UK and USA are public orientated, which means that regular news reports are made available to the general public as soon as possible. However, this can influence eyewitness accounts as the eyewitnesses are affected by what they hear around them and by what they read in the newspaper.

Studies have shown that where subjects are able to discuss their experience with other participants, they unconsciously their own memories to include things that they did not experience or witness themselves.

One strong influence is ‘peer pressure’. A witness may have a desire to help the investigation, or feel a strong sense of responsibility. This could lead to a ‘false memory’, or an overconfident testimony, which could incorrectly result in a guilty verdict.

The Solution

We have hundreds of real life case studies combined with scientific evidence that demonstrate the unreliability of eyewitness testimony. On the other hand, if eyewitness testimony is completely discredited and disregarded, then many vital leads in an investigation will never come to light.

There are ongoing efforts to apply findings from psychology experiments to assist eyewitness recall. For example, we know that subtle, unintentional feedback can have an effect on one’s confidence of memory recall. So the solution is to ensure the police conducting the lineup do not have any knowledge of the case and cannot unintentionally influence the witness.

Already in the UK there are strict rules (called the Turnbull Guidelines) in place surrounding eyewitness testimony. If a testimony is disputed by the defendant, the judge will assess the weight that the evidence will be given in court. There are many factors that the judge will take into consideration including; the length of time between testifying and the crime happening, conditions of the crime (light or dark), and whether the witness previously knew the accused.

Similar laws have also been recently implemented in the US, specifically in the New Jersey Supreme Court. These state that before the trial, the jury must be educated on the risks and possible dangers of putting too much weight on eyewitness testimony.

By introducing a more controlled environment for eyewitness testimony, and ensuring there is a better understanding of how it works, this should (hopefully) reduce the possibility of reaching the wrong verdict.

Steph McLean contributed this article; she works at Lenstore.co.uk, an ecommerce retailer where people can buy contact lenses online.